Science Daily November 16, 2022 The vulnerabilities of Global navigation satellite systems (GNSS) combined with the lack of a back-up system pose a severe risk to GNSS-dependent technologies. Researchers in the Netherlands used optical and wireless transmission schemes similar to those encountered in mobile communication networks, and exploiting spectrally efficient virtual wideband signals. The detrimental effects of multipath propagation were mitigated, thus enabling robust decimetre-level positioning and subnanosecond timing in a multipath-prone outdoor environment. They demonstrated that their system is independent of GNSS and offers superior performance through a constellation of radio transmitters, connected and time-synchronized at the subnanosecond level […]
Author Archives: Hema Viswanath
New communications technology: Super-fast optical lasers
Science Daily November 9, 2022 While enabling orders-of-magnitude gains in data rates, optical signals impose much stricter pointing requirements and are strongly affected by atmospheric turbulence. Researchers in Australia established a coherent 1550 nm link across turbulent atmosphere between a deployable optical terminal and a drone-mounted retroreflector. Through 10 Hz machine vision optical tracking with nested 200 Hz tip/tilt adaptive optics stabilisation, they corrected for pointing errors and atmospheric turbulence to maintain robust single mode fiber coupling, resulting in an uninterrupted 100 Gbps optical data link while tracking at angular rates of up to 1.5 deg/s, equivalent to that of […]
New strategy to effectively prevent component failures in metals
Phys.org November 11, 2022 Eliminating grain boundaries (GBs) is a primary approach to resisting high-temperature creep in metals which is responsible for component failures at high temperatures. Researchers in China found that grain boundaries in the nanograined single-phased alloy could be effectively stabilized through structural relaxation, and the creep performance of the alloy could be significantly enhanced at elevated temperatures. They demonstrated a creep resistance, with creep rates of ~10–7 per second under gigapascal stress at 700°C (~61% melting point), outperforming that of conventional superalloys. They plan to extend this principle to other engineering alloy families for high-temperature applications, including […]
New theory of electron spin to aid quantum devices
Phys.org November 10, 2022 Researchers at Caltech have developed a new theory and numerical calculations to predict spin decoherence in materials with high accuracy. They adapted a theory of electrical transport to study spin and discovered that this method can capture two main mechanisms governing spin decoherence in materials—spin scattering off atomic vibrations, and spin precession modified by atomic vibrations. They could predict spin decoherence times with an accuracy of a few percent of the measured values—down to a billionth of a second—and access microscopic details of spin motion beyond the reach of experiments. Their research tools—computers and quantum mechanics—can […]
Next generation material that adapts to its history
Nanowerk November 15, 2022 The responses of living systems dynamically adapt based on the repetition, intensity, and history of stimuli. Such plasticity is ubiquitous in biology, which is profoundly linked to memory and learning. Inspired by living systems, researchers in Finland synthesised micrometre-sized magnetic beads which were then stimulated by a magnetic field. When the magnet was on, the beads stacked up to form pillars. The strength of the magnetic field affects the shape of the pillars, which in turn affects how well they conduct electricity. When they exposed the beads to a quickly pulsing magnetic field, the material became […]
Novel nanowire fabrication technique paves way for next generation spintronics
Nanowerk November 9, 2022 Eliminating the etching process by directly fabricating nanowires onto the silicon substrate would lead to a marked improvement in the fabrication of spintronic devices. However, when directly fabricated nanowires are subjected to annealing, they tend to transform into droplets as a result of the internal stresses in the wire. Researchers in Japan have developed a new fabrication process to make L10-ordered CoPt nanowires on silicon/silicon dioxide (Si/SiO2) substrates. They coated a Si/SiO2 substrate with a material called a ‘resist’ and subjected it to electron beam lithography and evaporation to create a stencil for the nanowires, deposited […]
One-unit-cell thick semiconductors with room-temperature magnetism
Nanowerk November 15, 2022 Researchers in China have developed a confined-van der Waals epitaxial approach to synthesizing air-stable semiconducting cobalt ferrite nanosheets with thickness down to one unit cell using a facile chemical vapor deposition process. They demonstrated hard magnetic behavior and magnetic domain evolution by means of vibrating sample magnetometry, magnetic force microscopy and magneto-optical Kerr effect measurements, which showed high Curie temperature above 390 K and strong dimensionality effect. According to the researchers their work provides possibilities for numerous novel applications in computing, sensing and information storage…read more. Open Access TECHNICAL ARTICLE
Putting the brakes on lithium-ion batteries to prevent fires
Science Daily November 14, 2022 Researchers in China have developed a kind of novel shape-memorized current collector (SMCC), which can successfully brake battery thermal runaway at the battery internal overheating status. Unlike traditional current collectors made of commercial copper foils, SMCC is made of a micropatterned shape memory micron-sized film with copper deposition. SMCC displays ideal conductivity at normal temperatures and turns to be insulative at overheating temperatures. According to the researchers a battery consisting of an SMCC can run normally at temperatures lower than 90 °C, while it quickly achieves self-shutdown before the occurrence of battery combustion and explosion…read […]
Researchers develop a material that mimics how the brain stores information
Nanowerk November 8, 2022 While a precise modulation of magnetism is achieved when voltage is applied, much more uncontrolled is the spontaneous evolution of magneto-ionic systems upon removing the electric stimuli. An international team of researchers (Spain, Italy, Belgium) has demonstrated a voltage-controllable N ion accumulation effect at the outer surface of CoN films adjacent to a liquid electrolyte, which allows for the control of magneto-ionic properties both during and after voltage pulse actuation (i.e., stimulated, and post-stimulated behavior, respectively). This effect, which takes place when the CoN film thickness is below 50 nm and the voltage pulse frequency is […]
The transformation between different topological spin textures
Phys.org November 11, 2022 Skyrmions and bimerons are versatile topological spin textures that can be used as information bits for both classical and quantum computing. An international team of researchers (Japan, China, Australia) has demonstrated the creation of isolated skyrmions and their subsequent transformation to bimerons by harnessing the electric current-induced Oersted field and temperature-induced perpendicular magnetic anisotropy variation. The reversible transformation between skyrmions and bimerons was controlled by the current amplitude and scanning direction. Both skyrmions and bimerons could be created in the same system through the skyrmion-bimeron transformation and magnetization switching. Deformed skyrmion bubbles and chiral labyrinth domains […]